Search and rescue for pilots and other airborne personnel are among the military's most important life-saving missions in both peacetime and war, and time is always a critical factor. The extraordinary demands of these critical and dangerous missions have led to the development of several types of airborne survival equipment, including survival radios. Most survival radios use a complicated waveform to allow detection of the survivor or downed pilot. Consequently, they involve the implementation and application of complex communications electronic hardware to secretly recover the downed pilot. In many cases, this is for security and encryption purposes. Other known airborne survivability equipment methods involve using multiple fixed position locator terminals and a mobile survivor handset. One widely used military survival radio is the AN/ARS-6 Radio Set and it is an essential part of a system for military Combat Search and Rescue and it provides the rescue team with the identification, direction and distance to the AN/PRC-112 radio, which is part of the pilot's survival kit. The airborne guidance system locates missing pilots under harsh operating conditions and while concealing their location from hostile enemy forces during dangerous tactical engagements. However, the distance obtained by the present AN/ARS-6 to the survivor can be somewhat inaccurate by about 100 meters, which could be a critical distance when missions are conducted under stormy conditions or hostile fire where time is of the essence.
One potential solution for the lack of pinpoint accuracy that could substantially increase the speed and effectiveness of the rescue effort is to augment the airborne survivability equipment by installing currently available Global Positioning System (“GPS”) capabilities on the airborne search platforms. By adding GPS capability to the airborne search platforms and integrating GPS into the search and rescue mission it would be possible to determine a more precise location of the survivor to within about 10-20 meters and save valuable time during which the survivor faces extreme danger. Increasing the current accuracy of about 100 meters to a much smaller location of 10-20 meters would substantially increase the probability of quickly locating the downed pilot and saving the downed pilot minimizing exposure to hazards such as drowning, sharks and hostile enemy forces.
Although augmenting search equipment with GPS capability offers a number of advantages to the airborne search and rescue mission, GPS does suffer from a number of disadvantages, shortcomings and limitations. GPS receivers are susceptible to unintentional disruption from a number of causes including atmospheric effects, multipath errors, signal blockage from foliage and buildings and interference from other communications equipment, as well as deliberate disruption from enemy jamming. Augmenting the search and rescue effort with GPS could introduce errors, in the form of noise, in the calculations for GPS range from the satellite. Using current GPS capability with survival radio transponders like the AN/ARS-6(V) and AN/PRC-112 Radio Sets would, in some cases, add undesirable and dangerous risks of inaccuracy to the already demanding and critical performance parameters of the airborne search and rescue mission.
Thus, there has been a long-felt need for increased accuracy and reliability in airborne survivability equipment that does not suffer from the disadvantages, shortcomings and limitations of GPS disruption and complexity. Prior art survivability equipment typically involves a fixed to semi-mobile ground-based survivor transponder and a mobile search vehicle transponder that is usually deployed in a fixed or rotary wing aircraft. The present invention answers this long-felt need with a survivor locator system that advantageously employs a GPS receiver, a mechanism that enables communication with an encoded transponder/beacon signal and a phase matched antenna set in a mobile base station such as a helicopter to locate the downed pilot's transponder in a fixed position with the mobile base station's navigational parameters to quickly determine estimated distance and bearing data on the pilot's position with a known level of accuracy. The present invention provides airborne survival equipment that adds GPS capability to airborne search and rescue systems suffering from the disadvantages, shortcomings and limitations of inaccuracy, disruption and complex and expensive equipment.